Effects of hemodialysis and saline loading on body fluid compartments, plasma renin activity and blood pressure in patients on chronic hemodialysis.

The influence of one hemodialysis session and of subsequent loading by 1.5-2 liters N saline on blood pressure, PRA and body fluid compartments was assessed in seven patients with chronic renal failure on maintenance hemodialysis. Dialysis caused only slight decreases in plasma volume, ECV and in TEBS. Lying mean blood pressure by 5-10 mm Hg and PRA increased by 30%. Saline loading resulted in a significant increase in plasma volume by 0.4 liters and in blood pressure by 10-5 mm Hg, but in a decrease in PRA by 40%. The changes in mean blood pressure correlated positively with the changes in plasma volume, and negatively with the changes in PRA. It is concluded that the renin-angiotensin system in patients on chronic hemodialysis still functions as one of the adjustment mechanisms for the circulatory homeostasis, when challenged by volume loss or volume and sodium loading.